Powder coating compositions having improved mar and acid resistance

ABSTRACT

A thermosetting composition that includes a co-reactable solid, particulate mixture of a film forming material having functional groups and a crosslinking agent having at least two functional groups that are reactive with the functional groups in the film forming material. The crosslinking agent includes a copolymer having at least 30 mol % of alternating structural units of a residue from a donor monomer and a residue from one or more acrylic acceptor monomers. The thermosetting composition may coat a substrate by coalescing the composition to form a continuous film and curing the composition. The thermosetting composition may be included as part of a multi-component composite coating composition that includes an optional primer coat, a base coat deposited from a pigmented film-forming composition, and a transparent top coat applied over the base coat, where either the base coat, the transparent top coat, or both, are deposited from the thermosetting composition.

CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application is a Continuation-in-Part of U.S. applicationSer. No. 10/077,645, filed Feb. 15, 2002, entitled “ThermosettingCompositions Containing Alternating Copolymers of Isobutylene TypeMonomers,” which is-hereby incorporated by reference.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates generally to thermosettingcompositions that contain copolymers of vinyl monomers. Morespecifically, the present invention is directed to a co-reactable solidparticulate mixture thermosetting composition that includes functionalcopolymers containing isobutylene type monomers.

[0004] 2. Description of Related Art

[0005] Reducing the environmental impact of coating compositions, inparticular that associated with emissions into the air of volatileorganics during their use, has been an area of ongoing investigation anddevelopment in recent years. Accordingly, interest in powder coatingshas been increasing due, in part, to their inherently low volatileorganic content (VOC), which significantly, reduces air emissions duringthe application process. While both thermoplastic and thermoset coatingcompositions are commercially available, thermoset coatings aretypically more desirable because of their superior physical properties,e.g., hardness and solvent resistance.

[0006] Low VOC coatings are particularly desirable in the automotiveoriginal equipment manufacture (OEM) market due to the relatively largevolume of coatings that are used. However, in addition to therequirement of low VOC levels, automotive manufacturers have very strictperformance requirements of the coatings that are used. For example,automotive OEM clear top coats are typically required to have acombination of good exterior durability, acid etch and water spotresistance, and excellent gloss and appearance. While liquid top coatscontaining, for example, capped polyisocyanate and polyol components,can provide such properties, they have the undesirable drawback ofhigher VOC levels relative to powder coatings that have essentially zeroVOC levels.

[0007] Coating compositions containing polyol and capped polyisocyanatecomponents (“isocyanate cured coatings”) are known and have beendeveloped for use in a number of applications, such as industrial andautomotive OEM topcoats. Such isocyanate cured coating compositions aredescribed in, for example, U.S. Pat. Nos. 4,997,900, 5,439,896,5,508,337, 5,554,692, and 5,777,061. However, their use has been limiteddue to deficiencies in, for example, flow, appearance, and storagestability. Isocyanate cured coating compositions typically include acrosslinker having two or more capped isocyanate groups, e.g., a trimerof 1-isocyanato-3,3,5trimethyl-5-isocyanatomethylcyclohexane capped withe-caprolactam, and a hydroxy functional polymer, e.g., an acryliccopolymer prepared in part from a hydroxyalkyl acrylate and/ormethacrylate.

[0008] Solid particulate coating formulations referred to in theindustry as “powder coatings” are finding increasing use in paintingmetal substrates, both as primer coatings and as top or clear coats ofthe base coat and clear coat composite coatings. The automotive industryprovides corrosion protection and decorative appearance for motorvehicles by multilayered paint composites on the various types ofsurfaces of motor vehicles. The finishing layers of this compositeusually include the popular base coat clear coat composites. The basecoat is a pigmented layer and the clear coat is a nonpigmented or onlyslightly pigmented layer that is applied separately to the base coat andcured to some degree with the base coat. To provide improved coatingcomposites for motor vehicles, the industry is seeking solutions to theproblem of blemishes, smudges, and coating imperfections that occur dueto the action of acid rain and road dirt, and debris that may strikeareas of the vehicle. These strikes can result in unaesthetic marring ofthe clear coat. Mar resistance is the property of a coating film whichenables the film to remain unimpaired by light abrasion, impact, orpressure.

[0009] It would be desirable to develop thermosetting “powder coating”compositions that include functional, copolymers that provide excellentacid resistance and mar resistance and have low VOC levels.

SUMMARY OF THE INVENTION

[0010] The present invention is directed to a thermosetting compositionthat includes a co-reactable solid, particulate mixture of:

[0011] (a) a film forming material comprising functional groups; and

[0012] (b) a crosslinking agent having at least two functional groupsthat are reactive with the functional groups in the film formingmaterial (a) comprising a copolymer composition comprising at least 30mol % of residues having the following alternating structural units:

-[DM-AM]-

[0013] where DM represents a residue from a donor monomer having thefollowing structure (I):

[0014] where R¹ is linear or branched C₁ to C₄ alkyl, R² is selectedfrom the group consisting of methyl, linear, cyclic, or branched C₁ toC₂₀ alkyl, alkenyl, aryl, alkaryl, and aralkyl; and AM represents aresidue from one or more acrylic acceptor monomers.

[0015] The present invention is also directed to a method of coating asubstrate, including applying the above-described thermosettingcomposition to the substrate, coalescing the thermosetting compositionto form a substantially continuous film, and curing the thermosettingcomposition. The present invention is additionally directed tosubstrates coated using the method.

[0016] The present invention is further directed to a multi-componentcomposite coating composition that includes a base coat deposited from apigmented film-forming composition, and a transparent top coat appliedover the base coat, where either the base coat, the transparent topcoat, or both, are deposited from the above-described thermosettingcomposition. The present invention is additionally directed tosubstrates coated by the multi-component composite coating composition.

DETAILED DESCRIPTION OF THE INVENTION

[0017] Other than in the operating examples, or where otherwiseindicated, all numbers or expressions referring to quantities ofingredients, reaction conditions, etc. used in the specification andclaims are to be understood as modified in all instances by the term“about.” Various numerical ranges are disclosed in this patentapplication. Because these ranges are continuous, they include everyvalue between the minimum and maximum values. Unless expressly indicatedotherwise, the various numerical ranges specified in this applicationare approximations.

[0018] As used herein and in the claims, the terms “(meth)acrylate,”“(meth)acrylic,” and similar terms are meant to indicate the inclusionof the analogous acrylic and methacrylic and/or acrylate andmethacrylate based molecules.

[0019] As used herein, the term “copolymer composition” is meant toinclude a synthesized copolymer, as well as residues from initiators,catalysts, and other elements attendant to the synthesis of thecopolymer, but not covalently incorporated thereto. Such residues andother elements considered as part of the copolymer composition aretypically mixed or co-mingled with the copolymer such that they tend toremain with the copolymer when it is transferred between vessels orbetween solvent or dispersion media.

[0020] As used herein, the term “substantially free” is meant toindicate that a material is present as an incidental impurity. In otherwords, the material is not intentionally added to an indicatedcomposition, but may be present at minor or inconsequential levelsbecause it was carried over as an impurity as part of an intendedcomposition component.

[0021] The terms “donor monomer” and “acceptor monomer” are usedthroughout this application. With regard to the present invention, theterm “donor monomer” refers to monomers that have a polymerizable,ethylenically unsaturated group that has relatively high electrondensity in the ethylenic double bond, and the term “acceptor monomer”refers to monomers that have a polymerizable, ethylenically unsaturatedgroup that has relatively low electron density in the ethylenic doublebond. This concept has been quantified to an extent by the Alfrey-PriceQ-e scheme (Robert Z. Greenley; Polymer Handbook; Fourth Edition,Brandrup, Immergut and Gulke, editors, Wiley & Sons, New York, N.Y., pp.309-319 (1999)). All e values recited herein are those appearing in thePolymer Handbook unless otherwise indicated.

[0022] In the Q-e scheme, Q reflects the reactivity of a monomer and erepresents the polarity of a monomer, which indicates the electrondensity of a given monomer's polymerizable, ethylenically unsaturatedgroup. A positive value for e generally indicates that a monomer has arelatively low electron density and is an acceptor monomer, as is thecase for maleic anhydride, which has an e value of 3.69. A low ornegative value for e generally indicates that a monomer has a relativelyhigh electron density and is a donor monomer, as is the case for vinylethyl ether, which has an e value of −1.80.

[0023] As referred to herein, a strong acceptor monomer is meant toinclude those monomers with an e value greater than 2.0. The term “mildacceptor monomer” is meant to include those monomers with an e valuegreater than 0.5 up to and including those monomers with an e value of2.0. Conversely, the term “strong donor monomer” is meant to includethose monomers with an e value of less than −1.5, and the term “milddonor monomer” is meant to include those monomers with an e value ofless than 0.5 to those with an e value of −1.5.

[0024] The present invention is directed to a thermosetting compositionthat includes a film forming material comprising functional groups and acrosslinking agent having functional groups that are reactive with thefunctional groups in the film forming material.

[0025] As used herein and in the claims, the term “film formingmaterial” refers to a material that by itself or in combination with aco-reactive material, such as a crosslinking agent, is capable offorming a continuous film on a surface of a substrate. In an embodimentof the present invention, the film forming material may be a suitablepolymer. Suitable polymers include, but are not limited to, homopolymersand copolymers having functional groups selected from polyacrylates,polymethacrylates, polyesters, polyamides, polyethers, polysilanes, andpolysiloxanes. In a particular embodiment, the film forming material maybe a film forming acrylic copolymer having epoxy functional groups asdescribed in U.S. Pat. No. 6,277,917 to Jurgetz et al., which is hereinincorporated by reference. Preferably, the film forming material is asolid particulate material.

[0026] The crosslinking agent may be a copolymer composition thatcontains a functional group-containing copolymer having at least 30 mol%, in many cases at least 40 mol %, typically at least 50 mol %, in somecases at least 60 mol %, and in other cases at least 75 mol % ofresidues of the copolymer derived from alternating sequences of donormonomer—acceptor monomer pairs having the alternating monomer residueunits-of structure:

-[DM-AM]-

[0027] where DM represents a residue from a donor monomer and AMrepresents a residue from an acceptor monomer. The copolymer may be a100% alternating copolymer of DM and AM. More particularly, at least 15mol % of the copolymer comprises a donor monomer, which is anisobutylene-type monomer, having the following structure (I):

[0028] where R¹ is linear or branched C₁ to C₄ alkyl; R² is one or moreof methyl, linear, cyclic, or branched C₁ to C₂₀ alkyl, alkenyl, aryl,alkaryl, and aralkyl. Further, at least 15 mol % of the copolymerincludes an acrylic monomer as an acceptor monomer. The group R² mayinclude one or more functional groups selected from epoxy, carboxylicacid, hydroxy, thiol, amide, amine, oxazoline, aceto acetate, methylol,methylol ether, isocyanate, capped isocyanate, beta hydroxyalkamide, andcarbamate. Preferably, the crosslinking agent is a solid particulatematerial.

[0029] In an embodiment of the present invention, the copolymercrosslinking agent incorporates a substantial portion of alternatingresidues of a mild donor monomer as described by structure I and a mildacceptor monomer, which is an acrylic monomer. A non-limiting list ofpublished e values for monomers that may be included as monomersdescribed by structure I and acrylic monomers of the present inventionare shown in Table 2. TABLE 2 Alfrey-Price e values for SelectedMonomers e value Monomer Monomers of structure 1 Isobutylene −1.20¹Diisobutylene 0.49² Acrylic Monomers Acrylic Acid 0.88¹ Acrylamide 0.54¹Acrylonitrile 1.23¹ Methyl Acrylate 0.64¹ Ethyl Acrylate 0.55¹ ButylAcrylate 0.85¹ Benzyl acrylate 1.13¹ Glycidyl acrylate 1.28¹

[0030] Any suitable donor monomer may be used in the present invention.Suitable donor monomers that may be used include strong donor monomersand mild donor monomers. Suitable donor monomers include, but are notlimited to, isobutylene, diisobutylene, isoprene, dipentene, isoprenol,1-octene, and mixtures thereof. The present invention is particularlyuseful for preparing alternating copolymers where a mild donor moleculeis used. The present copolymers will, include a mild donor monomerdescribed by structures I, such as isobutylene and diisobutylene,1-octene, and isoprenol, and may additionally include other suitablemild donor monomers. The mild donor monomer of structure I is present inthe copolymer composition at a level of at least 15 mol %, in some casesat least 25 mol %, typically at least 30 mol % and in some cases atleast 35 mol %. The mild donor monomer of structures is present in thecopolymer composition at a level of up to 50 mol %, in some cases up to47.5 mol %, typically up to 45 mol %, and, in some cases, up to 40 mol%. The level of the mild donor monomer of structure I used is determinedby the properties that are to be incorporated into the copolymercomposition. Residues from the mild donor monomer of structure I may bepresent in the copolymer composition in any range of values inclusive ofthose stated above.

[0031] Suitable other donor monomers that may be used in the presentinvention include, but are not limited to, ethylene, butene, styrene,substituted styrenes, methyl styrene, substituted styrenes, vinylethers, vinyl esters, vinyl pyridines, divinyl benzene, vinylnaphthalene and divinyl naphthalene. Vinyl esters include vinyl estersof carboxylic acids, which include, but are not limited to, vinylacetate, vinyl butyrate, vinyl 3,4-dimethoxybenzoate, and vinylbenzoate. The use of other donor monomers is optional; when other donormonomers are present, they are present at a level of at least 0.01 mol %of the copolymer composition, often at least 0.1 mol %, typically atleast 1 mol %, and, in some cases, at least 2 mol %. The other donormonomers may be present at up to 25 mol %, in some cases up to 20 mol %,typically up to 10 mol %, and, in some cases, up to 5 mol %. The levelof other donor monomers used is determined by the properties that are tobe incorporated into the copolymer composition. Residues from the otherdonor monomers may be present in the copolymer composition in any rangeof values inclusive of those stated above.

[0032] The copolymer composition includes acceptor monomers as part ofthe alternating donor monomer—acceptor monomer units along the copolymerchain. Any suitable acceptor monomer may be used. Suitable acceptormonomers include strong acceptor monomers and mild acceptor monomers. Anon-limiting class of suitable acceptor monomers are those described bythe structure (II):

[0033] where W is selected from the group consisting of —CN, —X, and—C(=O)—Y; wherein Y is selected from the group consisting of —NR³ ₂,—O—R⁵—O—C(=O)—NR³ ₂, and —OR⁴; R³ is selected from the group consistingof H, linear or branched C₁ to C₂₀ alkyl, and linear or branched C₁ toC₂₀ alkylol; R⁴ is selected from the group consisting of H,poly(ethylene oxide), poly(propylene oxide), linear or branched C₁ toC₂₀ alkyl, alkylol, aryl and aralkyl,.linear or branched C₁ to C₂₀fluoroalkyl, fluoroaryl and fluoroaralkyl, a siloxane radical, apolysiloxane radical, an alkyl siloxane radical, an ethoxylatedtrimethylsilyl siloxane radical, and a propoxylated trimethylsilylsiloxane radical; R⁵ is a divalent linear or branched C₁ to C₂₀ alkyllinking group; and X is a halide.

[0034] A class of mild acceptor monomers that are included in thepresent copolymer composition are acrylic acceptor monomers. Suitableacrylic acceptor monomers include those described by structure (III):

[0035] where Y is selected from —NR³ ₂, —O—R⁵—O—C (=O) —NR³ ₂ and —OR⁴;R³ is selected from H, linear or branched C₁ to C₂₀ alkyl, and linear orbranched C₁ to C₂₀alkyl, aryl, and aralkyl containing one or morefunctional groups selected from the group of epoxy, carboxylic acid,hydroxy, thiol, amide, amine, oxazoline, aceto acetate, methylol,methylol ether, isocyanate, capped isocyanate, beta hydroxyalkamide, andcarbamate; R⁴ is selected from H, linear or branched C₁ to C₂₀ alkyl,aryl, and aralkyl containing one or more functional groups selected fromthe group of epoxy, carboxylic acid, hydroxy, thiol, amide, amine,oxazoline, aceto acetate, methylol, methylol ether, isocyanate, cappedisocyanate, beta hydroxyalkamide, and carbamate; and R⁵ is a divalentlinear or branched C₁ to C₂₀ alkyl linking group.

[0036] The acrylic acceptor monomers of structure III are present in thecopolymer composition at a level of at least 15 mol %, in some cases atleast 25 mol %, typically at least 30 mol %, and, in some cases, atleast 35 mol %. The acrylic acceptor monomers of structure III arepresent in the copolymer composition at a level of up to 50 mol %, insome cases up to 47.5 mol %, typically up to 45 mol %, and, in somecases, up to 40 mol %. The level of the acrylic acceptor monomers ofstructure III used is determined by the properties that are to beincorporated into the copolymer composition. Residues from the acrylicacceptor monomers of structure III may be present in the copolymercomposition in any range of values inclusive of those stated above.

[0037] Suitable other mild acceptor monomers that may be used in thepresent invention include, but are not limited to, acrylonitrile,methacrylonitrile, vinyl halides, crotonic acid, vinyl alkyl sulfonates,and acrolein. Vinyl halides include, but are not limited to, vinylchloride and vinylidene fluoride. The use of other mild acceptormonomers is optional; when other mild acceptor monomers are present,they are present at a level of at least 0.01 mol % of the copolymercomposition, often at least 0.1 mol %, typically at least 1 mol %, and,in some cases, at least 2 mol %. The other acceptor monomers may bepresent at up to 35 mol %, in some cases up to 25 mol %, typically up to15 mol %, and, in some cases, up to 10 mol %. The level of otheracceptor monomers used is determined by the properties that are to beincorporated into the copolymer composition. Residues from the otheracceptor monomers may be present in the copolymer composition in anyrange of values inclusive of those stated above.

[0038] In an embodiment of the present thermosetting composition, theacrylic acceptor monomers include one or more selected from hydroxyethylacrylate, hydroxypropyl acrylate, acrylic acid, dimethylaminoethylacrylate, acrylamide, glycidyl acrylate, glycidyl methacrylate, n-butoxymethyl acrylamide, hydroxyethyl methacrylate, hydroxypropylmethacrylate, methacrylic acid, methacrylamide, 2-carbamoyloxyethylacrylate, 2-carbamoyloxyethyl methacrylate, 2-carbamoyloxypropylacrylate, 2-carbamoyloxypropyl methacrylate, 2-isocyanatoethyl acrylate,2-isocyanatoethyl methacrylate, 2-isocyanatopropyl acrylate,2-isocyanatopropyl methacrylate, 2-oxazoline ethyl acrylate, 2-oxazolineethyl methacrylate, 2-oxazoline propyl acrylate, 2-oxazoline propylmethacrylate, aceto acetate ester of hydroxyethyl acrylate, acetoacetate ester of hydroxyethyl methacrylate, aceto acetate ester ofhydroxypropyl methacrylate, and aceto acetate ester of hydroxypropylacrylate.

[0039] In a further embodiment of the present invention, the acrylicmonomers include carboxylic acid functional acrylic monomers. In aparticular embodiment, the carboxylic acid functional acrylic monomer isacrylic acid.

[0040] The present copolymer has a molecular weight of at least 250, inmany cases at least 500, typically at least 1,000,and, in some cases, atleast 2,000. The present copolymer may have a molecular weight of up to1,000,000, in many cases up to. 500,000, typically up to 100,000, and,in some cases, up to 50,000. Certain applications will require that themolecular weight of the present copolymer not exceed 50,000, in somecases not exceed 30,000, in other cases not exceed 20,000, and, incertain instances, not exceed 16,000. The molecular weight of thecopolymer is selected based on the properties that are to beincorporated into the copolymer composition. The molecular weight of thecopolymer may vary in any range of values inclusive of those statedabove.

[0041] The polydispersity index (PDI) of the present copolymer is notalways critical. The polydispersity index of the copolymer is usuallyless than 4, in many cases less than 3.5, typically less than 3, and, insome cases, less than 2.5. As used herein, and in the claims,“polydispersity index” is determined from the following equation:(weight average molecular weight (Mw)/number average molecular weight(Mn)). A monodisperse polymer has a PDI of 1.0. Further, as used herein,Mn and Mw are determined from gel permeation chromatography usingpolystyrene standards.

[0042] The copolymer crosslinking agent of the present invention mayhave all of the incorporated monomer residues in an alternatingarchitecture. A non-limiting example of a copolymer segment having 100%alternating architecture of diisobutylene (DIIB) and an acrylic acid(AA) is shown by structure IV: (IV)-AA-DIIB-AA-DIIB-AA-DIIB-AA-DIIB-AA-DIIB-AA-DIIB-AA-

[0043] However, in most instances, the present copolymer crosslinkingagent will contain alternating segments and random segments as shown bystructure V, a copolymer of DIIB, AA and other monomers, M:

[0044] Structure V shows an embodiment of the present invention wherethe copolymer may include alternating segments, as shown in the boxes,and random segments, as shown by the underlined segments.

[0045] The random segments of the copolymer may contain donor oracceptor monomer residues that have not been incorporated into thecopolymer composition by way of an alternating architecture. The randomsegments of the copolymer composition may further include residues fromother ethylenically unsaturated monomers. As recited herein, allreferences to polymer segments derived from alternating sequences ofdonor monomer—acceptor monomer pairs are meant to include segments ofmonomer residues such as those shown by the boxes in structure V.

[0046] The other ethylenically unsaturated monomers include any suitablemonomer not traditionally categorized as being an acceptor monomer or adonor monomer.

[0047] The other ethylenically unsaturated monomers, residue of monomerM of structure V, is derived from at least one ethylenicallyunsaturated, radically polymerizable monomer. As used herein and in theclaims, “ethylenically unsaturated, radically polymerizable monomer” andlike terms are meant to include vinyl monomers, allylic monomers,olefins, and other ethylenically unsaturated monomers that are radicallypolymerizable and not classified as donor monomers or acceptor monomers.

[0048] Classes of vinyl monomers from which M may be derived include,but are not limited to, monomer residues derived from monomers of thegeneral formula VI:

[0049] where R¹¹, R¹², and R¹⁴ are independently selected from the groupconsisting of H, CF₃ straight or branched alkyl of 1 to 20 carbon atoms,aryl, unsaturated straight or branched alkenyl or alkynyl of 2 to 10carbon atoms, unsaturated straight or branched alkenyl of 2 to 6 carbonatoms substituted with a halogen, C₃-C₈ cycloalkyl, heterocyclyl, andphenyl; R₁₃ is selected from the group consisting of H, C₁-C₆ alkyl,COOR¹⁵, wherein R¹⁵ is selected from the group consisting of H, analkali metal, a C₁ to C₆ alkyl group, glycidyl, and aryl.

[0050] Specific examples of other, monomers, M, that may be used in thepresent invention include methacrylic monomers and allylic monomers.Residue of monomer M may be derived from at least one of alkylmethacrylate having from 1 to 20 carbon atoms in the alkyl group.Specific examples of alkyl methacrylates having from 1 to 20 carbonatoms in the alkyl group from which residue of monomer M may be derivedinclude, but are not limited to, methyl methacrylate, ethylmethacrylate, propyl methacrylate, isopropyl methacrylate, butylmethacrylate, isobutyl methacrylate, tert-butyl methacrylate,2-ethylhexyl methatrylate, lauryl methacrylate; isobornyl methacrylate,cyclohexyl methacrylate, and 3,3,5-trimethylcyclohexyl methacrylate, aswell as functional methacrylates, such as hydroxyalkyl methacrylates,oxirane functional methacrylates, and carboxylic acid functionalmethacrylates, such as methacrylic acid.

[0051] Residue of monomer M may also be selected from monomers havingmore than one methacrylate group, for example, methacrylic anhydride anddiethyleneglycol bis(methacrylate).

[0052] As used herein and in the claims, by “allylic monomer(s)” what ismeant is monomers containing substituted and/or unsubstituted allylicfunctionality, i.e., one or more radicals represented by the followinggeneral formula VII,

H2C═C(R¹⁰)—CH₂—  (VII)

[0053] where R¹⁰ is hydrogen, halogen, or a C₁ to C₄ alkyl group. Mostcommonly, R¹⁰ is hydrogen or methyl and, consequently, general formulaVII represents the unsubstituted (meth)allyl radical, which encompassesboth allyl and methallyl radicals. Examples of allylic monomers include,but are not limited to, (meth)allyl alcohol; (meth)allyl ethers, such asmethyl (meth)allyl ether; allyl esters of carboxylic acids, such as(meth)allyl acetate, (meth)allyl butyrate, (meth)allyl3,4-dimethoxybenzoate, and (meth)allyl benzoate.

[0054] The present copolymer composition is prepared by a methodincluding the steps of (a) providing a donor monomer compositioncomprising one or more donor monomers of structure I; (b) mixing anethylenically unsaturated monomer composition comprising one or moreacceptor monomers with (a) to form a total monomer composition; and (c)polymerizing the total monomer composition in the presence of a freeradical initiator. In an embodiment of the present invention, theethylenically unsaturated monomer composition includes monomers ofstructure III.

[0055] In an embodiment of the present method, the monomer of structureI is present at a molar excess based on the amount of acrylic acceptormonomer. Any amount of excess monomer of structure I may be used in thepresent invention in order to encourage the formation of the desiredalternating architecture. The excess amount of monomer of structure Imay be at least 10 mol. %, in some cases up to 25 mol %, typically up to50 mol %, and, in some cases, up to 100 mol % based on the amount ofacrylic acceptor monomer. When the molar excess of monomer of structureI is too high, the process may not be economical on a commercial scale.

[0056] In a further embodiment of the present method, the acrylicacceptor monomer is present in an amount of at least 15 mol %, in somecases 17.5 mol %, typically at least 20 mol %, and, in some cases, 25mol % of the total monomer composition. The acrylic, acceptor monomermay further be present in an amount up to 50 mol %, in some cases up to47.5 mol %, typically up to 45 mol %, and, in some cases, up to 40 mol %of the total monomer composition. The level of the acrylic acceptormonomers used is determined by the properties that are to beincorporated into the copolymer composition. The acrylic acceptormonomers may be present in the monomer composition in any range ofvalues inclusive of those stated above.

[0057] The ethylenically unsaturated monomer composition of the presentmethod may include other donor monomers as described above, as well asother monomers designated by M and described above. The use of othermild acceptor monomers is optional in the present method. When othermild acceptor monomers are present, they are present at a level of atleast 0.01 mol % of the copolymer composition, often at least 0.1 mol %,typically at least 1 mol %, and, in some cases, at least 2 mol % of thetotal monomer composition. The other acceptor monomers may be present atup to 35 mol %, in some cases up to 25 mol %, typically up to 15 mol %,and, in some cases, up to 10 mol % of the total monomer composition. Thelevel of other acceptor monomers used herein is determined by theproperties that are to be incorporated into the copolymer composition.Residues from the other acceptor monomers may be present in thecopolymer composition in any range of values inclusive of those statedabove.

[0058] The use of other monomers, M, is optional in the present method.When other monomers are present, they are present at a level of at least0.01 mol % of the copolymer composition, often at least 0.1 mol %,typically at least 1 mol %, and, in some cases, at least 2 mol %. Theother monomers may be present at up to 35 mol %, in some cases up to 25mol %, typically up to 15 mol %, and, in some cases, up to 10 mol %. Thelevel of other monomers used herein is determined by the properties thatare to be incorporated into the copolymer composition. Residues from theother monomers, M, may be present in the copolymer composition in anyrange of values inclusive of those stated above.

[0059] In an embodiment of the present method, an excess of monomer ofstructure I is used, and the unreacted monomer of structure I is removedfrom the resulting copolymer composition by evaporation. The removal ofunreacted monomer is typically facilitated by the application of avacuum to the reaction vessel.

[0060] Any suitable free radical initiator may be used in the presentinvention. Examples of suitable free radical initiators include, but arenot limited to, thermal free radical initiators, photo-initiators, andredox initiators. Examples of suitable thermal free radical initiatorsinclude, but are not limited to, peroxide compounds, azo compounds, andpersulfate compounds.

[0061] Examples of suitable peroxide compound initiators include, butare not limited to, hydrogen peroxide, methyl ethyl ketone peroxides,benzoyl peroxides, di-t-butyl peroxide, di-t-amyl peroxide, dicumylperoxide, diacyl peroxides, decanoyl peroxides, lauroyl peroxides,peroxydicarbonates, peroxyesters, dialkyl peroxides, hydroperoxides,peroxyketals, and mixtures thereof.

[0062] Examples of suitable azo compounds include, but are not limitedto, 4-4′-azobis(4-cyanovaleric acid),1-1′-azobiscyclohexanecarbonitrile), 2-2′-azobisisdbutyronitrile,2-2′-azobis(2-methylpropionamidine) dihydrochloride,2-2′-azobis(2-methylbutyronitrile), 2-2′-azobis(propionitrile),2-2′-azobis(2,4-dimethylvaleronitrile), 2-2′-azobis(valeronitrile),2,2′-azobis[2-methyl-N-(2-hydroxyethyl)propionamide],4,4′-azobis(4-cyanopentanoic acid),2,2′-azobis(N,N′-dimethyleneisobutyramidine),2,2′-azobis(2-amidinopropane) dihydrochloride,2,2′-azobis(N,N′-dimethyleneisobutyramidine) dihydrochloride, and2-(carbamoylazo)-isobutyronitrile.

[0063] In an embodiment of the present invention, the ethylenicallyunsaturated monomer composition and the free radical polymerizationinitiator are separately and simultaneously added to and mixed with thedonor monomer composition. The ethylenically unsaturated monomercomposition and the free radical polymerization initiator may be addedto the donor monomer composition over a period of at least 15 minutes,in some cases at least 20 minutes, typically at least 30 minutes, and,in some cases, at least 1 hour. The ethylenically unsaturated monomercomposition and the free radical polymerization initiator may further beadded to the donor monomer composition over a period of up to 24 hours,in some case up to 18 hours, typically up to 12 hours, and, in somecases, up to 8 hours. The time for adding the ethylenically unsaturatedmonomer must be sufficient to maintain a suitable excess of donormonomer of structure I over unreacted acrylic acceptor monomer toencourage the formation of donor monomer—acceptor monomer alternatingsegments. The addition time is not so long as to render the processeconomically unfeasible on a commercial scale. The addition time mayvary in any range of values inclusive of those stated above.

[0064] After mixing, or during addition and mixing, polymerization ofthe monomers takes place. The present polymerization method can be runat any suitable temperature. Suitable temperature for the present methodmay be ambient, at least 50° C., in many cases at least 60° C.,typically, at least 75° C., and, in some cases, at least 100° C.Suitable temperature for the present method may further be described asbeing up to 300° C., in many cases, up to 275° C., typically, up to 250°C., and, in some cases, up to 225° C. The temperature is typically highenough to encourage good reactivity from the monomers and initiatorsemployed. However, the volatility of the monomers and correspondingpartial pressures create a practical upper limit on temperaturedetermined by the pressure rating of the reaction vessel. Thepolymerization temperature may vary in any range of values inclusive ofthose stated above.

[0065] The present polymerization method can be run at any suitablepressure. A suitable pressure for the present method may be ambient, atleast 1 psi, in many cases, at least 5 psi, typically, at least 15 psi.,and, in some castes, at least 20 psi. Suitable pressures for the presentmethod may further be described as being up to 200 psi, in many cases,up to 175 psi, typically, up to 150 psi, and, in some cases, up to 125psi. The pressure is typically high enough to maintain the monomers andinitiators in a liquid phase. The pressures employed have a practicalupper limit based on the pressure rating of the reaction vesselemployed. The pressure during polymerization temperature may vary in anyrange of values inclusive of those stated above.

[0066] The copolymer that results from the present method may beutilized as, a starting material for the preparation of other polymersby using functional group transformations by methods known in the art.Functional groups that can be introduced by these methods are epoxy,carboxylic acid, hydroxy, thiol, amide, amine, oxazoline, aceto acetate,methylol, methylol ether, isocyanate, capped isocyanate, betahydroxyalkamide, and carbamate.

[0067] For example, a copolymer of the present method comprising methylacrylate will contain carbomethoxy groups. The carbomethoxy groups canbe hydrolyzed to carboxyl groups or transesterified with an alcohol toform the corresponding ester of the alcohol. Using ammonia, theaforementioned methyl acrylate copolymer can be converted to an amideor, using a primary or secondary amine, can be converted to thecorresponding N-substituted amide. Similarly, using a diamine such asethylene diamine, one can convert the aforementioned copolymer of thepresent method to an N-aminoethylamide or, with ethanolamine, to anN-hydroxyethylamide. The N-aminoethylamide functionality can be furtherconverted to an oxazoline by dehydration. The N-aminoethylamide can befurther reacted with a carbonate, such as propylene carbonate, toproduce the corresponding urethane functional copolymer. Thesetransformations can be carried out to convert all of the carbomethoxygroups or can be carried out in part, leaving some of the carbomethoxygroups intact.

[0068] The thermosetting composition is a co-reactable solid,particulate mixture, or powder. The thermosetting composition includes afilm forming material, including functional groups, and a crosslinkingagent having functional groups that are reactive with the functionalgroups in the film forming material. In the powder thermosettingcomposition, the film forming material may have functional groupsselected from epoxy, carboxylic acid, hydroxy, thiol, isocyanate, cappedisocyanate, amide, amine, aceto acetate, methylol, methylol ether,oxazoline carbamate, and beta-hydroxyalkylamide. The functional groupsof the copolymer may be one or more of epoxy, carboxylic acid, hydroxy,thiol, amide, amine, oxazoline, aceto acetate, methylol, methylol ether,isocyanate, capped isocyanate, beta hydtoxyalkamide and carbamate. Thefunctional groups of the present copolymer crosslinking agent will reactwith the functional groups in the film forming material.

[0069] The functional copolymer crosslinking agent typically has afunctional group equivalent weight of, from 100 to 5,000grams/equivalent, in some cases of from 250 to 1,000 grams/equivalent,and the equivalent ratio of film forming material functional groups tocopolymer crosslinking agent functional groups is within the range of1:3 to3:1. Typically, the copolymer crosslinking agent is present in anamount of from 1 to 45 percent by weight, based on total weight of resinsolids, and the film forming material is present in an amount of from 55to 99 percent by weight, based on total weight of resin solids.

[0070] In an embodiment of the present powder thermosetting composition,the film forming material includes a polymer that includes residues ofacrylate monomers, methacrylate monomers, and mixtures thereof, andfurther includes functional groups. When the film forming materialincludes a polymer, the polymer may have a number average molecularweight of from 500 to 30,000, in some cases 500 to, 16,000, and apolydispersity index of less than 4. Further, when the film formingmaterial includes a polymer, the polymer may have a functional groupequivalent weight of from 100 to 5,000 grams/equivalent, in some casesof from 250 to 1,000 grams/equivalent.

[0071] In a further embodiment of the present invention, the functionalgroups of the film forming material are selected from epoxy, carboxylicacid, hydroxy, thiol, isocyanate, capped isocyanate, amide, amine, acetoacetate, methylol, methylol ether, oxazoline carbamate, andbeta-hydroxyalkylamide and mixtures thereof; the functional groups ofthe copolymer crosslinking agent are selected from epoxy, carboxylicacid, hydroxy, thiol, amide, amine, oxazoline, aceto acetate, methylol,methylol ether, isocyanate, capped isocyanate, beta hydroxyalkamide, andcarbamate and mixtures thereof; and the functional groups of the filmforming material are reactive with those in the copolymer crosslinkingagent.

[0072] In an embodiment of the present powder thermosetting composition,the equivalent ratio functional group equivalents in the copolymercrosslinking agent to functional group equivalents in the film formingis within the range of 1:3 to 3:1.

[0073] In a further embodiment of the present powder thermosettingcomposition, the film forming material is present in an amount of from55 to 99 percent by weight, based on total weight of resin solids andthe functional copolymer crosslinking agent is present in an amount offrom 1 to 45 percent by weight, based on total weight of resin solids.

[0074] In an additional embodiment of the present invention, the filmforming material is a polymer that includes residues of monomerscontaining epoxy functional groups, and the acrylic acceptor monomers inthe copolymer crosslinking agent include one or more carboxylic acidfunctional acrylic monomers. In a particular non-limiting example ofthis embodiment, the film forming material includes an acrylic copolymerthat includes residues of epoxy functional monomers selected fromglycidyl acrylate, glycidyl methacrylate, allyl glycidyl ether, vinylglycidyl ether, and mixtures thereof; and residues of acrylate monomersand methacrylate monomers selected from linear and branched C₁ to C₂₀alkyl, aryl, alkaryl, and aralkyl esters of acrylic acid; C₁to C₂₀alkyl, aryl, alkaryl, and aralkyl esters of methacrylic acid; andmixtures thereof. Further to this particular embodiment, the presentcopolymer crosslinking agent has at least two functional groups that arereactive with the epoxy functional groups in the film forming material,and includes at least. 30 mol %. of the residues having the alternatingstructural units:

-[DM-AM]-

[0075] as defined above, where the donor monomer is selected fromisobutylene, diisobutylene, dipentene, isoprene, isoprenol, 1-octene,and mixtures thereof, and the acrylic acceptor monomer is selected fromacrylic acid and methacrylic acid.

[0076] When the functional groups of the copolymer crosslinking agentare hydroxy functional groups and the functional group of the filmforming material is a capped polyisocyanate, the capping group of thecapped polyisocyanate crosslinking agent may be one or more of hydroxyfunctional compounds, 1H-azoles, lactams, and ketoximes. The cappinggroup is one or more of phenol, p-hydroxy methylbenzoate,1H-1,2,4-triazole, 1H-2,5-dimethyl pyrazole, 2-propanone oxime,2-butanone oxime, cyclohexanone oxime, and e-caprolactam. Thepolyisocyanate of the capped polyisocyanate crosslinking agent is one ormore of 1,6-hexamethylene. diisocyanate, cyclohexane diisocyanate, α,α′-xylylene diisocyanate, α,α,α′,α′-tetramethylxylylene diisocyanate,1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane,2,4,,4-trimethyl hexamethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, diisocyanato-dicyclohexylmethane, dimers ofsaid polyisocyanates, and trimers of the polyisocyanates. The copolymercrosslinking agent having hydroxy functional groups typically has ahydroxy equivalent weight of from 100 to 10,000 grams/equivalent.

[0077] In another embodiment of the present powder thermosettingcomposition, the functional groups of the film forming material areepoxy functional groups, and the copolymer crosslinking agent hascarboxylic functional groups.

[0078] In an embodiment of the present invention, when the copolymercrosslinking agent has carboxylic functional groups, the thermosettingcomposition may include other suitable carboxylic crosslinking agents.In this embodiment, suitable other carboxylic acid crosslinking agentsinclude, but are not limited to, one or mote of C₄ to C₂₀ aliphaticcarboxylic acids, polymeric polyanhydrides, carboxylic acid functionalpolyesters, carboxylic acid functional polyurethanes, and mixturesthereof. Suitable C₄ to C₂₀, aliphatic carboxylic acids include, but arenot limited to, one or more of dodecanedioic acid, azelaic acid, adipicacid, 1,6-hexanedioic acid, succinic acid, pimelic acid, sebacic acid,maleic acid, citric acid, itaconic acid, aconitic acid, and mixturesthereof.

[0079] In a further embodiment of the powder thermosetting composition,the functional groups of the copolymer crosslinking agent are carboxylicfunctional groups, and the film forming material includes abeta-hydroxyalkylamide. The beta-hydroxyalkylamide is typically onerepresented by structure VIII:

[0080] where R²⁴ is H or C₁-C₅ alkyl; R²⁵ is H, C₁-C₅ alkyl, or a grouphaving structure IX:

[0081] for which R²⁴ is as described above; E is a chemical bond ormonovalent or polyvalent organic radical derived from saturated,unsaturated, or aromatic hydrocarbon radicals including substitutedhydrocarbon radicals containing from 2 to 20 carbon atoms; m is 1 or 2;n is from 0 to 2; and m+n is at least 2.

[0082] The powder thermosetting composition of the present invention mayalso include one or more cure catalysts for catalyzing the reactionbetween the crosslinking agent and the functional copolymer. Classes ofuseful catalysts include metal compounds, in particular, organic tincompounds, and tertiary amines. Examples of organic tin compoundsinclude, but are not limited to, tin(II) salts of carboxylic acids,e.g., tin(II), acetate, tin(II) octanoate, tin(II) ethylhexanoate andtin(II) laurate; tin(IV) compounds, e.g., dibutyltin oxide, dibutyltindichloride, dibutyltin diacetate, dibutyltin dilaurate, dibutyltinmaleate, and dioctyltin diacetate. Examples of suitable tertiary aminecatalysts include, but are not limited to, diazabicyclo[2.2.2]octane and1,5-diazabicyclo[4,3,0]non-5-ene. Preferred catalysts include tin(II)octanoate and dibutyltin(IV) dilaurate.

[0083] The powder thermosetting composition of the present invention mayalso include pigments and fillers. Examples of pigments include, but arenot limited to, inorganic pigments, e.g., titanium dioxide and ironoxides; organic pigments, e.g., phthalocyanines, anthraquinones,quinacridones, and thioindigos; and carbon blacks. Examples of fillersinclude, but are not limited to, silica, e.g., precipitated silicas,clay, and barium sulfate. When used in the composition of the presentinvention, pigments and fillers are typically present in amounts of from0.1 percent to 70 percent by weight based on total weight of thethermosetting composition. More often, the thermosetting composition ofthe present invention is used as a clear composition being substantiallyfree of pigments and fillers.

[0084] The powder thermosetting composition of the present invention mayoptionally contain additives such as waxes for flow and wetting, flowcontrol agents, e.g., poly(2-ethylhexyl)acrylate, degassing additivessuch as benzoin, adjuvant resin to modify and optimize coatingproperties, antioxidants, and ultraviolet (UV) light absorbers. Examplesof useful antioxidants and UV light absorbers include those availablecommercially from Ciba-Geigy under the trademarks IRGANOX and TINUVIN.These optional additives, when used, are typically present in amounts upto 20 percent by weight based on total weight of the thermosettingcomposition.

[0085] The powder thermosetting composition of the present invention istypically prepared by first dry blending the film forming polymer, thecrosslinking agent, and additives, such as flow control agents,degassing agents and catalysts, in a blender, e.g., a Henshel bladeblender. The blender is operated for a period of time sufficient toresult in a homogenous dry blend of the materials charged thereto. Thehomogenous dry blend is then melt blended in an extruder, e.g., a twinscrew co-rotating extruder, operated within a temperature range of 80°C. to 140° C., e.g., from 100° C. to 125° C. The extrudate of thethermosetting composition of the present invention is cooled and, whenused as a powder coating composition, is typically milled to an averageparticle size of from, for example, 15 to 80 microns or higher, in somecases, 15 to 30 microns.

[0086] The present invention is also directed to a method of coating asubstrate, which includes the steps of:

[0087] (A) applying a thermosetting composition to the substrate;

[0088] (B) coalescing the thermosetting composition to form asubstantially continuous film; and

[0089] (C) curing the thermosetting composition.

[0090] The thermosetting composition is typically the powderthermosetting composition described above. The thermosetting compositionincludes the copolymer crosslinking, agent of the present invention,which includes a functional copolymer as previously described, and afilm forming material having at least two functional groups that arereactive with the functional groups of the functional copolymercrosslinking agent.

[0091] The thermosetting composition of the present invention may beapplied to the substrate by any appropriate means that are known tothose of ordinary skill in the art. Generally, the thermosettingcomposition is in the form of a dry powder and is applied by sprayapplication. Alternatively, the powder can be slurried in a liquidmedium, such as water, and spray applied. Where the language“co-reactable solid, particulate mixture” is used in the specificationand claims, the thermosetting composition can be in dry powder form orin the form of a slurry.

[0092] When the substrate is electrically conductive, the thermosettingcomposition is typically electrostatically applied. Electrostatic sprayapplication generally involves drawing the thermosetting compositionfrom a fluidized bed and propelling it through a corona field. Theparticles of the thermosetting composition become charged as they passthrough the corona field and are attracted to and deposited upon theelectrically conductive substrate, which is grounded. As the chargedparticles begin to build up, the substrate becomes insulated, thuslimiting further particle deposition. This insulating phenomenontypically limits the film build of the deposited composition to amaximum of 10 to 12 mils (250 to 300 microns), in some cases, 3 to 6mils (75 to 150 microns).

[0093] Alternatively, when the substrate is not electrically conductive,for example as is the case with many plastic substrates, the substrateis typically preheated prior to application of the thermosettingcomposition. The preheated temperature of the substrate is equal to orgreater than that of the melting point of the thermosetting composition,but less than its cure temperature. With spray application overpreheated substrates, film builds of the thermosetting composition inexcess of 6 mils (150 microns) can be achieved, e.g., 10 to 20 mils (254to 508 microns).

[0094] After application to the substrate, the thermosetting compositionis then coalesced to form a substantially continuous film. Coalescing ofthe applied composition is generally achieved through the application ofheat at a temperature equal to or greater than that of the melting pointof the composition, but less than its cure temperature. In the case ofpreheated substrates, the application and coalescing steps can beachieved in essentially one step.

[0095] The coalesced thermosetting composition is next cured by theapplication of heat. As used herein and in the claims, by “cured” ismeant a three-dimensional crosslink network formed by covalent bondformation, e.g., between the reactive, functional groups of theco-reactant and the epoxy groups of the polymer. The temperature atwhich the thermosetting composition of the present invention cures isvariable and depends in part on the type and amount of catalyst used.Typically, the thermosetting composition has a cure temperature withinthe range of 120° C. to 180° C., in some cases, from 130° C. to 160° C.

[0096] The thermosetting compositions described above can be applied tovarious substrates to which they adhere, including wood; metals, such asferrous substrates and aluminum substrates; glass; plastic and sheetmolding compound based plastics.

[0097] The present invention is further directed to a multi-componentcomposite coating composition that includes:

[0098] (a) a base coat deposited from a pigmented film-formingcomposition; and

[0099] (b) a transparent top coat applied over the base coat, whereeither the base coat or the transparent top coat or both are depositedfrom a clear film-forming thermosetting composition including thepresent thermosetting composition. The multi-component composite coatingcomposition as described herein is commonly referred to as acolor-plus-clear coating composition.

[0100] The base coat may be deposited from a powder coating compositionas described above or from a liquid thermosetting composition. When thebase coat is deposited from a liquid thermosetting composition, thecomposition is allowed to coalesce to form a substantially continuousfilm on the substrate. Typically, the film thickness will be about 0.01to about 5 mils. (about 0.254 to about 127 microns), preferably about0.1 to about2 mils (about 2.54 to about 50.8 microns) in thickness. Thefilm is formed on the surface of the substrate by driving solvent, i.e.,organic solvent and/or water, out of the film by heating or by an airdrying period. Preferably, the heating will only be for a short periodof time, sufficient to ensure that any subsequently applied coatings canbe applied to the film without dissolving the composition. Suitabledrying conditions will depend on the particular composition but, ingeneral, a drying time of from about 1 to 5 minutes at a-temperature ofabout 68-250° F. (20-121° C.) will be adequate. More than one coat ofthe composition may be applied to develop the optimum appearance.Between coats, the previously applied coat may be flashed, that is,exposed to ambient conditions for about 1 to 20 minutes.

[0101] After application to the substrate, the liquid thermosettingcomposition, when used as the base coat, is then coalesced to form asubstantially continuous film. Coalescing of the applied composition isgenerally achieved through the application of heat at a temperatureequal to or greater than that of the melting point of the composition,but less than its cure temperature. In the case of preheated substrates,the application and coalescing steps can be achieved in essentially onestep.

[0102] The coalesced thermosetting composition is next cured by theapplication of heat. As used herein and in the claims, by “cured” ismeant a three-dimensional, crosslink network formed by covalent bondformation, e.g., between the reactive functional groups of the filmforming material and the crosslinking agent. The temperature at whichthe thermosetting composition of the present invention cures is variableand depends in part on the type and amount of catalyst used. Typically,the thermosetting composition has a cure temperature within the range of120° C. to 180° C., in some cases, from 130° C. to 160° C.

[0103] The pigmented film-forming composition from which the base coatis deposited can be any of the compositions useful in coatingsapplications, particularly automotive applications in whichcolor-plus-clear coating compositions are extensively used. Pigmentedfilm-forming compositions conventionally comprise a resinous binder anda pigment to act as a colorant. Particularly useful resinous binders areacrylic polymers, polyesters including alkyds, polyurethanes, and thecopolymer composition of the present invention.

[0104] The resinous binders for the pigmented film-forming base coatcomposition can be organic solvent-based materials, such as thosedescribed in U.S. Pat. No. 4,220,679, note column 2, line 24 throughcolumn 4, line 40. Also, water-based coating compositions, such as thosedescribed in U.S. Pat. Nos. 4,403,003, 4,147,679, and 5,071,904, can beused as the binder in the pigmented film-forming composition.

[0105] The pigmented film-forming base coat composition is colored andmay also contain metallic pigments. Examples of suitable pigments can befound in U.S. Pat. Nos. 4,220,679, 4,403,003, 4,147,679, and 5,071,904.

[0106] Ingredients that may be optionally present in the pigmentedfilm-forming base coat composition are those which are well known in theart of formulating surface coatings, and include surfactants, flowcontrol agents, thixotropic agents, fillers, anti-gassing agents,organic co-solvents, catalysts, and other customary auxiliaries.Examples of these optional materials and suitable amounts are describedin the aforementioned U.S. Pat. Nos. 4,220,679, 4,403,003, 4,147,679,and 5,071,904.

[0107] The pigmented film-forming base coat composition can be appliedto the substrate by any of the conventional coating techniques, such asbrushing, spraying, dipping, or flowing, but are most often applied byspraying. The usual spray techniques and equipment for air spraying,airless spraying, and electrostatic spraying employing either manual orautomatic methods can be used. The pigmented film-forming composition isapplied in an amount sufficient to provide a base coat having a filmthickness typically of 0.1 to 5 mils (2.5 to 125 microns) and preferably0.1 to 2 mils (2.5 to 50 microns).

[0108] After deposition of the pigmented film-forming base coatcomposition onto the substrate, and prior to application of thetransparent top coat, the base coat can be cured or alternatively dried.In drying the deposited base coat, organic solvent and/or water isdriven out of the base coat film by heating or the passage of air overits surface. Suitable drying conditions will depend on the particularbase coat composition used and on the ambient humidity in the case ofcertain water-based compositions. In general, drying of the depositedbase coat is performed over a period of from 1 to 15 minutes and at atemperature of 21° C. to 93° C.

[0109] The transparent top coat is applied over the deposited base coatby any of the methods by which coatings are known to be applied. In anembodiment of the present invention, the transparent top coat is appliedby electrostatic spray application as described previously herein. Whenthe transparent top coat is applied over a deposited base coat that hasbeen dried, the two coatings can be co-cured to form the multi-componentcomposite coating composition of the present invention. Both the basecoat and top coat are heated together to conjointly cure the two layers.Typically, curing conditions of 130° C. to 160° C. for a period of 20to30 minutes are employed. The transparent top coat typically has athickness within the range of 0.5 to 6 mils (13 to 150 microns), e.g.,from 1 to 3 mils (25 to 75 microns).

[0110] In an embodiment of the present invention, the multi-componentcomposite coating composition includes:

[0111] (a) a primer coat deposited by electrocoating a conductivesubstrate serving as a cathode in an electrical circuit comprising thecathode and an anode, the cathode and the anode being immersed in anaqueous electrocoating composition, by passing an electric currentbetween the cathode and the anode to cause deposition of theelectrocoating composition on the substrate as a substantiallycontinuous film;

[0112] (b) a base coat applied over the primer coat, where the base coatis deposited from a pigmented film-forming composition; and

[0113] (c) a transparent top coat applied over the base coat, whereinthe base coat or the transparent top coat or both are deposited from aclear film-forming thermosetting composition including the presentthermosetting composition.

[0114] In this particular embodiment of the present invention, the basecoat and transparent top coat are as described above, and the primercoat is deposited from a thermosetting composition that includes aresinous phase dispersed in an aqueous medium. The resinous phaseincludes an ungelled copolymer composition that includes a copolymerhaving a functional group containing one or more active hydrogen groupsand a suitable ionic group, and a curing agent having at least twofunctional groups that are reactive with the active hydrogen groups ofthe copolymer. Suitable ionic groups include anionic groups and cationicgroups. A non-limiting example of a suitable cationic group is an aminesalt group. Electrodeposition compositions are well known in the art andare described, for example, in U.S. Pat. Nos. 4,468,307; 4,493,056;5,096,556 and 5,820,987.

[0115] After electrodeposition of the primer coat, a pigmentedfilm-forming base coat composition is typically applied over theprimer-coated substrate. The base coat can be cured or alternativelydried. In drying the deposited base coat, organic solvent and/or wateris driven out of the base coat film by heating or the passage of airover its surface. Suitable drying conditions will depend on theparticular base coat composition used and on the ambient humidity in thecase of certain water-based compositions. In general, drying of thedeposited base coat is performed over a period of from 1 to 15 minutesand at a temperature of 21° C. to 93° C.

[0116] The transparent top coat may be applied over the deposited basecoat by any of the methods by which coatings are known to be applied. Inan embodiment of the present invention, the top coat is applied byelectrostatic spray application as described previously herein. When thetop coat is applied over a deposited base coat that has been dried, thetwo coatings can be co-cured to form the primed multi-componentcomposite coating composition of the present invention. Both the basecoat and top coat are heated together to conjointly cure the two layers.Typically, curing conditions of *130° C. to 160° C. for a period of 20to 30 minutes are employed. The transparent top coat typically has athickness within the range of 0.5 to 6 mils (13 to 150 microns), e.g.from 1 to 3 mils (25 to 75 microns).

[0117] In an embodiment of the present invention, additional coatinglayers such as a primer-surfacer may be applied to the electrodepositedprimer layer prior to application of the base coat.

[0118] As used herein and in the claims, the term “primer surfacer”refers to a primer composition for use under a subsequently appliedtopcoating composition, and includes such materials as thermoplasticand/or crosslinking (e.g., thermosetting) film-forming resins generallyknown in the art of organic coating compositions. Suitable primers andprimer-surfacers include spray applied primers, as are known to thoseskilled in the art. Examples of suitable primers include severalavailable from PPG Industries, Inc., Pittsburgh, Pa., as DPX-1791,DPX-1804, DSPX-1537, GPXH-5379, and 1177-225A.

[0119] As is described in U.S. Pat. No. 5,356,973 to Taljan et al., thespray applied primer surfacer can be applied to the electrocoat beforeapplying a base coat and/or topcoating. For example, substrates, such aspanels, can be electrocoated with ED-11 electrodepositable coating fromPPG Industries Inc. and can be primed with a commercially available PPGIndustries primer surfacer coded E 730G305. This primer surfacer can becured for 25 minutes at 329° F. (165° C.). Another example of a suitableprimer surfacer can be the two-package, acrylic urethane primer surfacerknown as K200/K201 more fully disclosed in U.S. Pat. No. 5,239,012 toMcEntire, et al. and U.S. Pat. No. 5,182,355 to Martz et al., for suchprimer surfacer. This primer may be sanded with No. 400 grit paper andsealed with DP-40/401, which is a two-component epoxy primer which wasreduced 100 percent by volume with a thinner, DTU 800. The K200/K201,DP-40/401, and DTU 800 are all available from PPG Industries, Inc.

[0120] An additional primer-surfacer is that available from PPGIndustries, Inc. as E-5584. It is reducible with 2-butoxyethylacetate toa viscosity of 23 seconds as measured with a No. 4 Ford cup. This primersurfacer can be sprayed automatically and cured by flashing at ambientconditions for 15 minutes followed by heating for around 30 minutes ataround 325° F. (165° C.) to produce coatings that can have dry filmthickness of around 30 microns. The cured film is may be sanded smoothwith 500 grit sandpaper. Useful automatic spraying for both the primersurfacer and the clear coat is the SPRAYMATION 310160 Automatic TestPanel Spray Unit available from SPRAYMATION Inc. The useable spray gunis a Binks Model 610, with open gun pressure 60 psi (4.22 kg/cm²) andtraverse speed of around 80 rpm.

[0121] Another suitable primer surfacer can be the water dispersedprimer-surfacer composition with a combination of three essentialresinous film-forming or binder ingredients as disclosed in U.S. Pat.No. 4,303,581 to Levine et al., which is herein incorporated byreference. The primer surfacer has a) 50 to.90 percent of a highmolecular addition copolymer of a styrenic monomer with acrylic monomersin latex form, b) about 5 to 40 percent of a water soluble epoxy esterresin, and c) about 5 to 20 percent of at least one water soluble orwater dispersible aminoplast resin. All percents are based on percent byweight of the total of the binder ingredients.

[0122] The present invention is more particularly described in thefollowing examples, which are intended to be illustrative only, sincenumerous modifications and variations therein will be apparent to thoseskilled in the art. Unless otherwise specified, all parts andpercentages are by weight.

EXAMPLE 1

[0123] The ingredients in Table 1 were used to synthesize an alternatingcopolymer, diisobutylene-alt-acrylic acid/butyl acrylate, Example A.TABLE 1 Parts by weight Ingredients (grams) Charge 1 Diisobutylene 3136n-Methoxypropanol¹⁵ 1400 Charge 2 t-Amylperoxy(2- 196 ethyl hexanoate)¹⁶Charge 3 Acrylic acid 633.6 Butyl Acrylate 665.6

[0124] Charge 1 was added to a reaction flask equipped with an agitator,a thermocouple, and a N₂ inlet, placed under an N₂ blanket and heated to103° C. Charge 2 was added to the reaction flask over 4 hours. After 15minutes, Charge 3 was added to the reaction flask over 4 hours. Duringthe monomer addition, the temperature was maintained at 103° C. AfterCharges 2 and 3 were in, the reaction flask, the reaction mixture washeld for 2 hours. The reaction flask was then cooled to 25° C. GasChromatography (GC) analysis of the reaction mixture showed that all ofthe acrylates were reacted. The reaction flask was then equipped forsimple vacuum distillation and the reaction mixture heated to 80° C. toremove the unreacted diisobutylene and solvent The solids of theresulting polymer were determined to be 98.3 wt. %, after drying at 110°C. for one hour. The copolymer had a number average molecular weight,Mn=1430and polydispersity Mw/Mn=1.8 (determined by gel permeationchromatography using polystyrene standards). The acid value of thepowder was 207.1.

[0125] The ingredients in Table 2 were used to synthesize an alternatingcopolymer, diisobutylene-alt-acrylic acid/butyl acrylate, Example B.TABLE 2 Parts by weight Ingredients (grams) Charge 1 Diisobutylene 784n-Methoxypropanol¹⁵ 75 Charge 2 t-Amylperoxy(2- 73.5 ethyl hexanoate)¹⁶Charge 3 Acrylic acid 158.4 Butyl Acrylate 166.4

[0126] Charge 1 was added to a reaction flask equipped with an agitator,a thermocouple, and a N₂ inlet, placed under a blanket of N₂, and heatedto 103° C. Charge 2 was added to the reaction flask over 4 hours. After15 minutes, Charge 3 was added to the reaction flask over 4 hours.During the monomer addition, the temperature was maintained at 103° C.After Charge 2 and Charge 3 were in the reaction flask, the reactionmixture was held for 2 hours. The reaction flask was then cooled to 25°C. GC analysis of the reaction mixture showed that all of the acrylateswere reacted. The reaction flask was then equipped for simple vacuumdistillation, and the reaction mixture heated to 80° C. to remove theunreacted diisobutylene and solvent. The solids of the resulting polymerwere determined to be 98.52 wt. %, at 110° C. for one hour. Thecopolymer had Mn=1310 and Mw/Mn=1.9 (determined by gel permeationchromatography using polystyrene standards). The acid value of thepowder was 196.8.

[0127] The ingredients in Table 3 were used to synthesize an alternatingcopolymer, diisobutylene-alt-acrylic acid/butyl acrylate/isobornylacrylate, Example C. TABLE 3 Parts by weight Ingredients (grams) Charge1 Diisobutylene 784 n-Methoxypropanol¹⁵ 350 Charge 2 t-Amylperoxy(2- 49ethyl hexanoate)¹⁶ Charge 3 Acrylic Acid 129.6 Butyl Acrylate 128Isobornyl Acrylate 145.6

[0128] Charge 1 was added to a reaction flask equipped with an agitator,a thermocouple, and a N₂ inlet, placed under a blanket of N₂₁ and heatedto 103° C. Charge 2 was added to the reaction flask over 4 hours. After15 minutes, Charge 3 was added to the reaction flask over 4 hours.During the, monomer addition, the temperature was maintained at 103° C.After Charge 2 and Charge 3 were in the reaction flask, the reactionmixture was held for 2 hours. The reaction flask was then cooled to 25°C. GC analysis of the reaction mixture showed that all of the acrylateswere reacted. The reaction flask was then equipped for simple vacuumdistillation, and the reaction mixture heated to 80° C. to remove theunreacted diisobutylene and the solvent. The solids of the resultingpolymer were determined to be 97.84 wt. %, at 110° C. for one hour. Thecopolymer had Mn=1430 and Mw/Mn=1.9 (determined by gel permeationchromatography using polystyrene standards). The acid value of thepowder was 148.7.

[0129] The ingredients in Table 4 were used to synthesize an alternatingcopolymer, isobutylene-alt-acrylic acid, Example D. Parts by weightIngredients (grams) Charge 1 Isobutylene 1,000 Methyl isobutyl ketone1,500 Charge 2 Di-t-amyl Peroxide 100 Charge 3 Acrylic Acid 1,000

[0130] Charge 1 was added to a stainless steel pressure reaction vesselequipped with an agitator, a thermocouple, and a N₂ inlet, placed undera 5 psi N₂ pad, and heated to 150° C. Charge 2 was added to the reactionflask over a 2.5-hour period. After 15 minutes, Charge 3 was added tothe reaction flask over a 2-hour period. During the monomer addition,the temperature was maintained at 150° C. and pressure at 250 psi. AfterCharge 2 and Charge 3 were in the reaction flask, the reaction mixturewas held for 2 hours. The reaction flask was then cooled to 25° C. GCanalysis of the reaction mixture showed that all of the acrylic acid wasreacted. The reaction flask was then equipped for simple vacuumdistillation and the reaction mixture heated to 115° C. to remove theunreacted isobutylene and solvent. The solids of the resulting polymerwere determined to be 100 wt. %, at 110° C. for one hour. The copolymerhad Mn=1580 and Mw/Mn=2.2 (determined by gel permeation chromatographyusing polystyrene standards). The acid value of the powder was 406.

[0131] Epoxy-acid powder clear coat compositions identified as ExamplesE through I in Table 5 were prepared using the components and amounts(parts by weight) shown, and processed in the following manner. Thecomponents were blended in a Henschel Blender for 60 to 90 seconds. Themixtures were then extruded through a Werner & Pfleider co-rotating twinscrew extruder at a 450 RPM screw speed and an extrudate temperature of100° C. to 125° C. The extruded material was then ground to a meanparticle size of 17 to 27 μm using an ACM 2 (Air Classifying Mill fromHosakowa Micron Powder Systems). The finished powders wereelectrostatically sprayed onto test panels and evaluated for appearance.TABLE 5 Example E Description Comparative Example F Example G Example HExample I GMA Functional Acrylic¹⁷ 53.20 44.00 43.28 38.93 48.82Dodecanedioic Acid 20.86 9.06 8.95 8.29 9.78 Polymer of Example A 21.34Polymer of Example B 22.17 Polymer of Example C 27.18 Polymer of ExampleD 15.8 Benzoin 0.20 0.20 0.20 0.20 0.20 Wax C Micropowder¹⁸ 0.60 0.600.60 0.60 0.60 Tinuvin 144¹⁹ 2.00 2.00 2.00 2.00 2.00 CGL-1545²⁰ 2.002.00 2.00 2.00 2.00 HCA-1²¹ 1.00 2.00 2.00 2.00 2.00 ARMEEN M2C²² 1.301.30 1.30 1.30 1.30 Acrylic Flow Additive²³ 17.50 17.50 17.50 17.5017.50 Total 100.00 100.00 100.00 100.00

[0132] The powder coating composition of Examples E through I wereprepared for testing in the following manner. The test panels,pre-coated with an electrocoat primer commercially available from PPGIndustries, Inc. as ED5000 were coated with a primer/surfacer and abasecoat by spray application to a film thickness of 1.4 mils (36microns) and 0.4 mils (9.4 microns), respectively, with a blacksolventborne primer commercially available from Akzo-Nobel Corp., and awaterborne black basecoat from BASF Corporation. The basecoat panelswere flashed 10 minutes at 176° F. (80° C.) before electrostaticallyapplying the powder clearcoat compositions of Examples E through I. Thepowder coatings were applied at 2.2-2.6 mils (55-65 microns) filmthickness and cured for 30 minutes at 293° F. (145° C.). The panels werethen tested for coating properties, including acid resistance. The acidresistance test used was a 36% sulfuric acid solution applied by 50 μLdrops to a panel heated to 65° C. One drop is applied on the panel everyminute for 30 minutes. At the end of the test, the panel is rinsed withdeionized water and rated for damage. A + indicates a moderateimprovement over the control. A ++ indicates a major improvement overthe control.

[0133] Mar resistance was evaluated using an Atlas Mar Tester. A 2 inchby 2 inch piece of 2 micron abrasive paper. (available from 3M, St.Paul, Minn.) was placed over a felt cloth clamped to an acrylic fingeron the arm of the instrument. A set often double rubs were run on panelsprepared as described above. The panels were washed with cool tap waterand dried. Mar resistance was evaluated as the percentage of the 20°Gloss value which was retained after the surface was marred by the martester. Mar resistance (Mar: 21 μ) was measured as: MarResistance=(Marred Gloss/Original Gloss)×100. A + indicates a moderateimprovement over the control. Results are reported in Table 6. TABLE 6Example E Example Example Example Example Comparative F G H I AcidResistance Damage Control ++ ++ ++ ++ Mar Resistance Mar: 2μControl + + + +

[0134] The data presented in Table 6 illustrates that the powderclearcoat compositions of the present invention (Examples F, G, H, andI) provide improved acid resistance and mar resistance over that of theComparative Example E.

EXAMPLE 2

[0135] The ingredients in Table 7 were used to synthesize an alternatingcopolymer, diisobutylene-alt-hydroxy ethyl acrylate/methylacrylate/isobornyl acrylate, Example J. TABLE 7 Parts by weightIngredients (grams) Charge 1 Diisobutylene 1,568 n-Methoxypropanol¹⁵ 200Charge 2 t-Amylperoxy(2- 24.5 ethyl hexanoate)¹⁶ Charge 3 Hydroxyethyl255.5 acrylate 223.6 Methyl acrylate 158.4 Isobornyl Acrylate

[0136] Charge 1 was added to a reaction flask equipped with an agitator,a thermocouple, and a N₂ inlet, placed under a blanket of N₂, and heatedto 103° C. Charge 2 was added to the reaction flask over a 4-hourperiod. After 15 minutes, Charge 3 was added to the reaction flask overa 4-hour period. During the monomer addition, the temperature wasmaintained at 103° C. After Charge 2 and Charge 3 were in the reactionflask, the reaction mixture was held for 2 hours. The reaction flask wasthen cooled to 25° C. GC analysis of the reaction mixture showed thatall of the acrylates were reacted. The reaction flask was then equippedfor simple vacuum distillation and the reaction mixture heated to 80° C.to remove the unreacted diisobutylene and solvent. The solids of theresulting polymer were determined to be 97.8 wt. %, determined at 110°C. for one hour. The copolymer had Mn=1700 and Mw/Mn=5.1 (determined bygel permeation chromatography using polystyrene standards). The hydroxylnumber of the powder was 142.6.

[0137] A powder coating was prepared as described in Table 8 using thecomponents and amounts (parts by weight) shown. TABLE 8 IngredientsExample K Polymer of Example J 232 Uretadione- 180 butanediol adduct²⁵TiO₂ Pigment²⁶ 200 Benzoin 2 Dibutyl tin 2 dilaurate on silica²⁷

[0138] The powder coating was prepared and processed in the followingmanner. The components were blended in a Prism Blender for 15 to 30seconds. The mixtures were then extruded through a Werner & Pfleiderco-rotating twin screw extruder at a 450 RPM screw speed and anextrudate temperature of 100° C. to 125° C. The extruded material wascooled to room temperature and then ground to a median particle size of30 to 50 microns, using an ACM Grinder (Air Classifying Mill from MicronPowder Systems, Summit, N.J.). Cold rolled steel test panels pretreatedwith Bonderite 1000 were obtained from ACT Laboratories. The finishedpowders were electrostatically sprayed onto test panels and baked for 20minutes at 380° F. (193° C.).

[0139] Gloss was measured with a Haze-gloss Reflectometer Model 4601available from BYK-Gardner. The Gloss measured at 20° was 73.6. and-theGloss measured at 60° was 87.9. Solvent resistance was determined withmethylethyl ketone (MEK). A cloth was saturated with MEK and rubbed backand forth (double rub) 50 times. No change to the appearance of thecoating was observed.

[0140] The present invention has been described with reference tospecific details of particular embodiments thereof. It will beappreciated by those skilled in the art that changes could be made tothe embodiments described above without departing from the broadinventive concept thereof. It is not intended that such details beregarded as limitations upon the scope of the invention except insofaras and to the extent that they are included in the accompanying claims.

1-21. (canceled)
 22. A multi-component composite coating compositioncomprising: (a) a base coat deposited from a pigmented film-formingcomposition; and (b) a transparent top coat applied over the base coat,wherein either the base coat or the transparent top coat or both isdeposited from the thermosetting composition comprising a co-reactablesolid, particulate mixture of: (c) a film forming material comprisingfunctional groups; and (d) a crosslinking agent having at least twofunctional groups that are reactive with the functional groups in thefilm forming material (c) comprising a copolymer composition comprisingat least 30 mol % of residues having the following alternatingstructural units: -[DM-AM]- wherein DM represents a residue from a donormonomer selected from the group consisting of isobutylene,diisobutylene, dipentene, isoprene, isoprenol, 1-octene, and mixturesthereof; and AM represents a residue from one or more acrylic acceptormonomers.
 23. The multi-component coating composition of claim 22,wherein the transparent top coat (b) is deposited from the thermosettingcomposition.
 24. A multi-component composite coating compositioncomprising: (a) a base coat deposited from a pigmented film-formingcomposition; and (b) a transparent top coat applied over the base coat,wherein either the base coat or the transparent top coat or both isdeposited from the thermosetting composition comprising a co-reactablesolid, particulate mixture of: (c) a film forming material comprising anacrylic copolymer comprised of residues of epoxy functional monomersselected from the group consisting of glycidyl acrylate, glycidylmethacrylate, allyl glycidyl ether, vinyl glycidyl ether, and mixturesthereof; and residues of acrylate monomers and methacrylate monomersselected from the group consisting of linear and branched C₁ to C₂₀alkyl, aryl, alkaryl, and aralkyl esters of acrylic acid, C₁ to C₂₀alkyl, aryl, alkaryl, and aralkyl esters of methacrylic acid andmixtures thereof; and (d) a crosslinking agent having at least twofunctional groups that are reactive with the functional groups in thefilm forming material (c) comprising a copolymer comprised of at least30 mol % of residues having the following alternating structural units:-[DM-AM]- wherein DM represents a residue from a donor monomer selectedfrom the group consisting of isobutylene, diisobutylene, dipentene,isoprene, isoprenol, 1-octene, and mixtures thereof; and AM represents aresidue from one or more acrylic acceptor monomers selected from thegroup consisting of acrylic acid and methacrylic acid.
 25. Themulti-component coating composition of claim 24, wherein the transparenttop coat (b) is deposited from the thermosetting composition comprisinga co-reactable solid, particulate mixture of: (c) a film formingmaterial comprising functional groups; and (d) a crosslinking agenthaving at least two functional groups that are reactive with thefunctional groups in the film forming material (c) comprising acopolymer composition comprising at least 30 mol % of residues havingthe following alternating structural units: -[DM-AM]- wherein DMrepresents a residue from a donor monomer selected from the groupconsisting of isobutylene, diisobutylene, dipentene, isoprene,isoprenol, 1-octene, and mixtures thereof; and AM represents a residuefrom one or more acrylic acceptor monomers.
 26. A multi-componentcomposite coating composition comprising: (a) a primer coat deposited byelectrocoating a conductive substrate serving as a cathode in anelectrical circuit comprising the cathode and an anode, the cathode andthe anode being immersed in an aqueous electrocoating composition, bypassing an electric current between the cathode and the anode to causedeposition of the electrocoating composition on the substrate as asubstantially continuous film; (b) a base coat applied over the primercoat, wherein the base coat is deposited from a pigmented film-formingcomposition; and (c) a transparent top coat applied over the base coat,wherein the base coat or the transparent top coat or both is depositedfrom a clear film-forming thermosetting composition comprising thethermosetting composition comprising a co-reactable solid, particulatemixture of: (d) a film forming material comprising functional groups;and (e) a crosslinking agent having at least two functional groups thatare reactive with the functional groups in the film forming material (d)comprising a copolymer composition comprising at least 30 mol % ofresidues having the following alternating structural units: -[DM-AM]-wherein DM represents a residue from a donor monomer selected from thegroup consisting of isobutylene, diisobutylene, dipentene, isoprene,isoprenol, 1-octene, and mixtures thereof; and AM represents a residuefrom one or more acrylic acceptor monomers.
 27. The multi-componentcoating composition of claim 26, wherein the transparent top coat (c) isdeposited from the thermosetting composition.
 28. A multi-componentcomposite coating composition comprising: (a) a primer coat deposited byelectrocoating a conductive substrate serving as a cathode in anelectrical circuit comprising the cathode and an anode, the cathode andthe anode being immersed in an aqueous electrocoating composition, bypassing an electric current between the cathode and the anode to causedeposition of the electrocoating composition on the substrate as asubstantially continuous film; (b) a base coat applied over the primercoat, wherein the base coat is deposited from a pigmented film-formingcomposition; and (c) a transparent top coat applied over the base coat,wherein the base coat or the transparent top coat or both is depositedfrom the thermosetting composition comprising a co-reactable solid,particulate mixture of: (d) a film forming material comprising anacrylic copolymer comprised of residues of epoxy functional monomersselected from the group consisting of glycidyl acrylate, qlycidylmethacrylate, allyl glycidyl ether, vinyl glycidyl ether, and mixturesthereof; and residues of acrylate monomers and methacrylate monomersselected from the group consisting of linear and branched C₁ to C₂₀alkyl, aryl, alkaryl, and aralkyl esters of acrylic acid, C₁ to C₂₀alkyl, aryl, alkaryl, and aralkyl esters of methacrylic acid andmixtures thereof; and (e) a crosslinking agent having at least twofunctional groups that are reactive with the functional groups in thefilm forming material (d) comprising a copolymer comprised of at least30 mol % of residues having the following alternating structural units:-[DM-AM]- wherein DM represents a residue from a donor monomer selectedfrom the group consisting of isobutylene, diisobutylene, dipentene,isoprene, isoprenol, 1-octene, and mixtures thereof; and AM represents aresidue from one or more acrylic acceptor monomers selected from thegroup consisting of acrylic acid and methacrylic acid.
 29. Themulti-component coating composition of claim 28, wherein the transparenttop coat (c) is deposited from the thermosetting composition.
 30. Themulti-component coating composition of claim 28, wherein after theprimer coat in (a) is applied and before the base coat in (b) isapplied, a primer surfacer is applied over the primer coat.
 31. Themulti-component coating composition of claim 30, wherein the primersurfacer is spray applied.
 32. A substrate coated with themulti-component composite coating composition of claim
 22. 33. Asubstrate coated with the multi-component composite coating compositionof claim
 24. 34. A substrate coated with the multi-component compositecoating composition of claim
 26. 35. A substrate coated with themulti-component composite coating composition of claim
 28. 36. Asubstrate coated with the multi-component composite coating compositionof claim 30.